The use of various types of sensors and systems which control sensors on most modern vehicles is well known in the art. There are many different types of sensors on the market that are currently used to measure such items as temperature, acceleration, load, deformation, stress, excitation, fuel quantity and altitude, to name just a few. Various methods of using these types of sensors are well known in the art and there are several systems that use multiple combinations of sensors throughout transportation vehicles.
In these prior art sensor systems each sensor utilized in the system is typically incorporated with a circuit that creates a drive signal to excite the sensor. These drive circuits commonly consist of a first set of analog circuits that provide a particular sensor with an analog excitation signal. Once the sensor being driven receives the analog excitation signal the sensor will generate a response signal which is communicated to a second set of analog circuits. After leaving the second set of analog circuits, which is connected with the output of the sensor being driven, the output signal is fed to the instrument associated with displaying or controlling the parameter measured.
Some of the systems currently employed with these sensors use microprocessors to control the sensor system. In these systems, a microprocessor is connected with a digital to analog converter which creates the analog drive signal used to excite the sensors. In addition, an analog to digital converter is usually connected to the output of the sensor being driven to convert the response signal received by the sensor back to a digital format. After the response signal is converted to a digital signal it is communicated as an input to the microprocessor. Once the response signal is converted to a digital signal and received by the microprocessor, parametric measurement contained in the response signal is used to control an instrument or control system much like the above-described analog system.
The problem with these prior art systems is that each sensor system utilizes its own unique set of circuitry to control each unique sensor. For example, the circuitry used to drive an accelerometer is separate and independent of the circuitry used to control temperature sensors. The lack of a standard sensor interface increases manufacturing and maintenance costs due to the increase in the number of components necessary to build and operate each individual sensor's circuitry. In addition, since each sensor is associated with a separate instrument or control system, other systems on a vehicle cannot utilize or incorporate the information being gathered by another sensor system. Additionally, as the number of components increases so does the likelihood of system failure because the reliability of each system depends on the reliability of each component used in that system.
Due to the complexity of modern aircraft systems, a need exists for a universal sensor interface system that can provide common hardware and software to drive a variety of different sensors. This system should be able to communicate with a multiplicity of sensor types in a common communications format without the necessity of using several kinds of different circuits to control each individual sensor. A universal sensor interface that requires less components also improves the reliability of the overall sensor system. A more versatile and robust sensor interface is desired that will give users of sensor systems the ability to quickly modify and adapt current sensor interfaces to new types of sensors without having to replace entire sensor systems. Thus, a universal sensor interface is needed that can communicate with almost any sensor type without requiring separate circuitry to control each type of sensor used in the sensing system.